The authors prospectively investigated 20 ankylosing spondylitis patients with 11 years of mean disease duration. The researched variables were related to patients activity and severity of symptoms, as well to the main axial skeleton radiological changes. The results showed that all the patients presented different degrees of radiological sacroiliitis, while 90% revealed apophyseal joints ankylosis, therefore demonstrating the importance of these radiological signs for the diagnosis of the ankylosing spondylitis.